FAQ
TL;DR: To wire DRLs with handbrake‑off activation, use a relay on ignition power and include a 5A fuse—"An additional 5A fuse can be added." [Elektroda, czyt, post #16631645]
Why it matters: This setup stops DRLs from lighting while parked with the handbrake on, then turns them on when you drive.
Who this is for: DIY car owners retrofitting DRLs without a dedicated controller, especially VW Passat B5 owners.
Quick Facts
- Typical hookup: +12V after ignition to relay coil, reference to position-light feed, DRLs on relay contacts. [Elektroda, Fredw, post #16631523]
- Add a single inline 5A fuse near the power source to protect the DRL circuit. [Elektroda, czyt, post #16631645]
- Handbrake switch may be negative-switched; plan relay logic accordingly. [Elektroda, Manius19888, post #16631466]
- VW modules support DRL modes; NA mode turns DRLs off with handbrake applied. [Elektroda, Heinzek, post #16633360]
- A diagram-based “German-style” relay solution was shared for combining signals. [Elektroda, Heinzek, post #16632031]
How do I wire DRLs so they stay off with the handbrake on, then turn on when released?
Use a relay coil fed from ignition +12V and switched by the handbrake signal. Combine with a diode-protected tap from the position light if needed for logic. Place DRLs on the relay’s switched contacts. Add a 5A fuse on the supply. [Elektroda, Heinzek, post #16632031]
Where should I tap ignition and lighting wires on a Passat B5 (pre-facelift)?
Take switched +12V from an ignition-on circuit to the relay coil. For the “lights-on” reference, tap the position-light wire at one headlamp. Keep the DRL load on the relay contacts, not on the small-gauge lighting wire. [Elektroda, Fredw, post #16631523]
Do I need a DRL controller, or will standard relays handle this?
You can do it with standard relays and a diode as control logic. Many installations work fine without a dedicated DRL module if wired cleanly and fused. A controller is optional convenience. [Elektroda, Fredw, post #16631523]
What fuse size should I use for aftermarket DRLs?
Use a single inline 5A fuse close to the battery or ignition feed. This protects the DRL circuit from shorts and wiring faults during installation and operation. [Elektroda, czyt, post #16631645]
My handbrake switch outputs ground (negative). Will this still work?
Yes. Many handbrake switches are ground-switched. Wire the relay coil with ignition +12V on one side and the handbrake ground on the other. The coil energizes only when the brake is released. [Elektroda, Manius19888, post #16631466]
Is it legal to have DRLs turn off when the handbrake is applied?
Regulations vary. A user noted local rules require DRLs with ignition, while others mention OEM modes that extinguish with the handbrake. Check your local road code before wiring. [Elektroda, Freddy, post #16633419]
What about cars with a CAN bus—does this change the approach?
It can. Some vehicles route lighting through control modules. Direct taps may trigger errors. Older cars are simpler; newer CAN-managed cars may require coding or module integration instead. [Elektroda, Fredw, post #16631523]
What DRL modes exist in VW group cars, and which matches handbrake-off behavior?
Two common modes are referenced: Scandinavian (low beam + rear) and North America (front only). In NA mode, DRLs switch off when the handbrake is applied. “When the handbrake is applied, they go out.” [Elektroda, Heinzek, post #16633360]
Can I use a thyristor to manage the handbrake signal?
Avoid it here. On DC, a thyristor latches on until the anode-cathode voltage is removed, which can keep DRLs on unintentionally. A relay and diode solution is safer. [Elektroda, Freddy, post #16632696]
How can I stop DRLs from turning on during cold starts while parked?
Gate the relay coil with the handbrake signal. With the brake applied at startup, the coil stays de-energized and DRLs remain off. Release the brake to light the DRLs. [Elektroda, Manius19888, post #16631925]
Is there a shared diagram for combining ignition, position light, and handbrake signals?
Yes. A contributor posted a diagram showing how to combine these inputs so DRLs behave “in German.” Study the schematic before cutting wires. [Elektroda, Heinzek, post #16632031]
Should the handbrake ever control exterior lights while driving?
One experienced user clarified the handbrake should not affect exterior lights during normal driving. Design your logic to avoid unintended cutoffs at stops. [Elektroda, Fredw, post #16633321]
What is a CAN bus, in simple terms?
Controller Area Network (CAN) is a vehicle data network that lets modules share signals over two wires. Lighting behavior may be software-controlled on CAN cars, affecting DRL retrofits. [Bosch, 1991]
I don’t want to custom-wire this. Should I buy a DRL controller?
You can. The original poster considered a module with this function. A controller with handbrake input simplifies wiring and may add dimming features. [Elektroda, Manius19888, post #16631634]
Quick 3-step: How do I implement the relay-and-handbrake DRL setup?
- Add a 5A inline fuse on an ignition-on +12V feed; run to relay coil and common.
- Connect the coil’s other side to the handbrake switch line; include a diode if combining with position-light logic.
- Wire DRLs to the relay’s switched output; ground DRLs to chassis. [Elektroda, czyt, post #16631645]
I was looking for a pattern and I can't find it 
